Pests

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Ants Back to Top

Argentine Ants Wikipedia
Argentine Ants Credit: Penarc, Wikipedia

The Argentine ant, Linepithema humile (formerly Iridomyrmex humilis), is an ant native to northern Argentina, Uruguay, Paraguay, Bolivia and southern Brazil. It is an invasive species that has been established in many Mediterranean climate areas, inadvertently introduced by humans to many places, including South Africa, New Zealand, Japan, Easter Island, Australia, Europe, Hawaii, and the continental United States.

The worker ants are 1.6–2.8 millimetres (0.06–0.11 in) long[4][5][dubious – discuss] and can easily squeeze through cracks and holes as small as 1 millimetre (0.04 in) in size. Queens are 4.2–6.4 millimetres (0.17–0.25 in) long,[4] much smaller than other species of ants. These ants will set up quarters in the ground, in cracks in concrete walls, in spaces between boards and timbers, even among belongings in human dwellings. In natural areas, they generally nest shallowly in loose leaf litter or beneath small stones, due to their poor ability to dig deeper nests. However, if a deeper nesting ant species abandons their nest, Argentine ant colonies will readily take over the space.

According to research published in Insectes Sociaux in 2009, it was discovered that ants from three Argentine ant supercolonies in America, Europe, and Japan, that were previously thought to be separate, were in fact most likely to be genetically related. The three colonies in question were one in Europe, stretching 6,000 km (3,700 mi) along the Mediterranean coast, the "Californian large" colony, stretching 900 km (560 mi) along the coast of California, and a third on the west coast of Japan.

Like workers in many other ant species, Argentine ant workers are unable to lay reproductive eggs but can direct the development of eggs into reproductive females; the production of males appears to be controlled by the amount of food available to the larvae.[16] Argentine ant colonies almost invariably have many reproductive queens, as many as eight for every 1,000 workers. The queens seldom or never disperse in winged form. Instead, colonies reproduce by budding off into new units. As few as ten workers and a single queen can establish a new colony.

The seasonal low occurs in mid-winter, when 90% of a representative colony consisted of workers and the remainder of queens, and no reproductive activity and minimal birthing. Eggs are produced in late-winter, nearly all of which hatch into sexual forms by May. Mating occurs after the females emerge. Worker production increases steadily from mid-March to October, after which their numbers are not replenished; thus, their numbers drop steadily over the winter months.

Colonies in the Argentine ant’s native habitat are kept within a range of ten to one hundred meters by colonies of interspecific and intraspecific rivals. As the colonies expand, they appear to form fluctuating territory borders, which contract and expand on a seasonal and conditional basis. There is an expansive push outward in the summer months, with a retreating motion in the winter. This has to do with soil moisture and temperature conditions. At the edges of these borders are either rival L. humile colonies or other obstacles that prevent further expansion, such as an inhospitable environment for nesting.

Odourous House AntWikipedia
Tapinoma Sessile Credit: AntWeb.org, Wikipedia

Tapinoma sessile is a species of small ant that goes by the common names odorous house ant, sugar ant, stink ant, and coconut ant. Their colonies are polydomous (consist of multiple nests) and polygynous (contain multiple reproducing queens). Like many social insects, T. sessile employs complex foraging strategies, allocates food depending on environmental conditions, and engages in competition with other insect species.

These ants can be found in a huge diversity of habitats, including within houses. They forage mainly for honeydew, which is produced by aphids and scale insects that are guarded and tended by the ants, as well as floral nectar and other sugary foods.[citation needed] They are common household pests and are attracted to sources of water and sweets.

Little is known about the lifespan of the ant, though it has been shown that queens live at least 8 months (and probably much longer), workers at least a few months (and show every indication of living as long as queens), while males appear to live only approximately a week.

This odorous house ant is tough; injured workers have been observed to continue living and working with little hindrance. Some queens with crushed abdomens still lay eggs, and there are documented instances of T. sessile queens surviving without food or water for over two months. They also appear highly tolerant to heat and cold. These ants are difficult to remove from the home. When crushed, these ants leave a smell which leads to their nickname "stink ant".

This species of ant demonstrates a dominance hierarchy system, consisting of a queen and subordinate workers. The larger colonies themselves vary in size from a few hundred to tens of thousands of individuals. The bigger colonies usually have multiple queens. The queens lay the eggs and then incubate between 11–26 days. The larva stage then lasts between 13–29 days, and the pre-pupal and pupal stages last between 10–24 days.

It is also found that the rate of trophallactic feeding depends on the number of ants per nest, and the quality of food available. When the number of donors is kept constant, but the number of total individuals in increased, more individuals test positive for the food marker. This indicates that more individuals are eating, but the amount they eat is less. If the number of donors was doubled, and the size of the overall population increased, the number of individuals receiving food more than doubled, again indicating that the number of individuals fed increased, but that the per capita amount of food consumed decreased. The ants prefer sugar and protein food sources over lipids, and this preference did not change seasonally. When specific sugar sources were studied the ants preferred sucrose over other sugars, such as fructose and glucose.

When searching for food, primary orientation is when ants are exploring a new terrain without the guidance of odor trails. Secondary orientation is when terrain has been explored, and there are pre-existing odor trails which ants use to orient themselves. When T. sessile ants are orientating themselves for the first time they often rely on topography. The major types of elements they rely on are bilaterally elevated, bilaterally depressed, unilaterally elevated, and unilaterally depressed. They use these types of surfaces to orient along, and lay the first odor trails, which can then be followed in the future, to the food source, by other ants.

It was also found that the polydomy, having multiple colonies to have access to multiple food sources, is seasonal in this ant species. The colony will overwinter in a single nest, and then during spring and summer when resources are more abundant they will form multiple nests. This allows them to better use food sources that might be spread out. During the winter they will return again to the same nest location. Seasonal polydomy is rather rare, and only found in 10% of all polydomous species. Although seasonal polydomy is rare and not found in many ant species there are many ant species, including T. sessile, which move even within a season. Immigration is common and allows them to forage for better food.

Seasonal activity patterns of the ants were also studied, and corresponding to the seasonal polydomy, it was observed that the ants displayed the most activity between March and September and displayed almost no activity from October to December. Daily activity patterns were also studied. In March T. sessile foraged during the day, but in April that pattern changed and the ant began to forage during both day and night. Throughout most of the summer the ant has low levels of activity during all twenty-four hours.

This species is a scavenger/predator ant that will eat most household foods, especially those that contain sugar, as well as other insects. Indoors they will colonize near heat sources or in insulation. In hot and dry situations, nests have been found in house plants and even in the lids of toilets. Outdoors they tend to colonize under rocks and exposed soil. They appear, however, to form colonies virtually anywhere, in a variety of conditions.

They appear to be more likely to invade homes after rain (which washes away the honeydew they collect).

Carpenter AntWikipedia
Carpenter Ant Credit: Muhammad Mahdi Karim, Wikipedia

Carpenter ants (Camponotus spp.) are large (0.3 to 1.0 in or 0.76 to 2.54 cm) ants indigenous to many forested parts of the world.

They build nests inside wood consisting of galleries chewed out with their mandibles, preferably in dead, damp wood. They do not consume the wood, however, unlike termites. Sometimes, carpenter ants hollow out sections of trees. They also commonly infest wooden buildings and structures, and are a widespread nuisance and major cause of structural damage. However, their ability to excavate wood helps in forest decomposition. One of the most familiar species associated with human habitation in the United States is the black carpenter ant (Camponotus pennsylvanicus). The genus includes over 1,000 species.

Carpenter ant species reside both outdoors and indoors in moist, decaying, or hollow wood, most commonly in forest environments. They cut "galleries" into the wood grain to provide passageways for movement from section to section of the nest. Certain parts of a house, such as around and under windows, roof eaves, decks and porches, are more likely to be infested by carpenter ants because these areas are most vulnerable to moisture.

Carpenter ants have been known to construct extensive underground tunneling systems. These systems often lead to an end at some food source – often aphid colonies, where the ants extract and feed on honeydew. These tunneling systems also often exist in trees. The colonies typically include a central "parent" colony surrounded and supplemented by smaller satellite colonies.

Carpenter ants are considered both predators and scavengers. These ants are foragers that typically eat parts of other dead insects or substances derived from other insects. Common foods for them include insect parts, "honeydew" produced by aphids, or extrafloral nectar from plants. They are also known for eating other sugary liquids such as honey, syrup, or juices. Carpenter ants can increase the survivability of aphids when they tend them. They tend many aphid species but can also express preference for specific ones.

Most species of carpenter ants forage at night. When foraging, they usually collect and consume dead insects. Some species less commonly collect live insects. When they discover a dead insect, workers surround it and extract its bodily fluids to be carried back to the nest. The remaining chitin-based shell is left behind. Occasionally, the ants bring the chitinous head of the insect back to the nest, where they also extract its inner tissue. The ants can forage individually or in small or large groups, though they often opt to do so individually. Different colonies in close proximity may have overlapping foraging regions, though they typically do not assist each other in foraging. Their main food sources normally include proteins and carbohydrates. Instances of carpenter ants bleeding Chinese elm trees for the sap have been observed in the northern Arizona region. These instances may be rare as the colonies vastly exceeded the standard size of carpenter ant colonies else where. When workers find food sources, they communicate this information to the rest of the nest. They use biochemical pheromones to mark the shortest path that can be taken from the nest to the source. When a sizable number of workers follows this trail, the strength of the cue increases and a foraging trail is established. This ends when the food source is depleted. The workers will then feed the queen and the larvae by consuming the food they have found, and regurgitating the food at the nest. Foraging trails can either be under or above ground.

Although carpenter ants do not tend to be extremely aggressive, they have developed mechanisms to maximize their provision from a food source when that same food source is visited by a competing organism. This is accomplished in different ways. Sometimes they colonize an area near a relatively static food supply. More often, they develop a systemic way to visit the food source with alternating trips by different individual ants or groups. This allows them to decrease the gains of intruders because the intruders tend to visit in a scattered, random, and unorganized manner. The ants, however, visit the sources systematically such that they lower the mean standing crop. They tend to visit more resource-dense food areas in an attempt to minimize resource availability for others. That is, the more systematic the foraging behavior of the ants, the more random that of its competitors.

Contrary to popular belief, carpenter ants do not actually eat wood because they are unable to digest cellulose. They only create tunnels and nests within it.

Carpenter ants work to build the nests that house eggs in environments with usually high humidity due to their sensitivity to environmental humidity. These nests are called primary nests. Satellite nests are constructed once the primary nest is established and has begun to mature. Residents of satellite nests include older larvae, pupae, and some winged individuals. Only eggs, the newly hatched larvae, workers, and the queen reside in the primary nests. As satellite nests do not have environmentally sensitive eggs, the ants can construct them in rather diverse locations that can actually be relatively dry. Some species, like Camponotus vagus, builds the nest in a dry place, usually in wood.

When conditions are warm and humid, winged males and females participate in a nuptial flight. They emerge from their satellite nests and females mate with a number of males while in flight. The males die after mating. These newly fertilized queens discard their wings and search for new areas to establish primary nests. The queens build new nests and deposit around 20 eggs, nurturing them as they grow until worker ants emerge. The worker ants eventually assist her in caring for the brood as she lays more eggs. After a few years, reproductive winged ants are born, allowing for the making of new colonies. Again, satellite nests will be established and the process will repeat itself.

As in most other social insect species, individual interaction is heavily influenced by the queen. The queen can influence individuals with odors called pheromones, which can have different effects. Some pheromones have been known to calm workers, while others have been known to excite them. Pheromonal cues from ovipositing queens have a stronger effect on worker ants than those of virgin queens.

Carpenter ants can damage wood used in the construction of buildings. They can leave behind a sawdust-like material called frass that provides clues to their nesting location. Carpenter ant galleries are smooth and very different from termite-damaged areas, which have mud packed into the hollowed-out areas. Carpenter ants can be identified by the general presence of one upward protruding node, looking like a spike, at the "waist" attachment between the thorax and abdomen (petiole). Control involves application of insecticides in various forms including dusts and liquids. The dusts are injected directly into galleries and voids where the carpenter ants are living. The liquids are applied in areas where foraging ants are likely to pick the material up and spread the poison to the colony upon returning.

FleasBack to Top

FleasWikipedia
Flea, under electron microscope Credit: CDC/Janice Haney Carr, Wikipedia

Fleas feed on a wide variety of warm-blooded vertebrates including humans, dogs, cats, rabbits, squirrels, ferrets, rats, mice and birds. Fleas normally specialise in one host species or group of species, but can often feed but not reproduce on other species. Ceratophyllus gallinae affects poultry as well as wild birds. As well as the degree of relatedness of a potential host to the flea's original host, it has been shown that avian fleas that exploit a range of hosts, only parasitise species with low immune responses. In general, host specificity decreases as the size of the host species decreases. Another factor is the opportunities available to the flea to change host species; this is smaller in colonially nesting birds, where the flea may never encounter another species, than it is in solitary nesting birds. A large, long-lived host provides a stable environment that favours host-specific parasites.

One theory of human hairlessness is that the loss of hair helped humans to reduce their burden of fleas and other ectoparasites.

In many species, fleas are principally a nuisance to their hosts, causing an itching sensation which in turn causes the host to try to remove the pest by biting, pecking or scratching. Fleas are not simply a source of annoyance, however. Flea bites cause a slightly raised, swollen itching spot to form; this has a single puncture point at the centre, like a mosquito bite. Besides this, the eczematous itchy skin disease flea allergy dermatitis is common in many host species, including dogs and cats. The bites often appear in clusters or lines of two bites, and can remain itchy and inflamed for up to several weeks afterwards. Fleas can lead to hair loss as a result of frequent scratching and biting by the animal, and can cause anemia in extreme cases.

Fleas are vectors for viral, bacterial and rickettsial diseases of humans and other animals, as well as of protozoan and helminth parasites. Bacterial diseases carried by fleas include murine or endemic typhus and bubonic plague. Fleas can transmit Rickettsia typhi, Rickettsia felis, Bartonella henselae, and the myxomatosis virus. They can carry Hymenolepiasis tapeworms and Trypanosome protozoans. The chigoe flea or jigger (Tunga penetrans) causes the disease tungiasis, a major public health problem around the world. Fleas that specialize as parasites on specific mammals may use other mammals as hosts; thus, humans may be bitten by cat and dog fleas.

Fleas have a significant economic impact. In America alone, approximately $2.8 billion is spent annually on flea-related veterinary bills and another $1.6 billion annually for flea treatment with pet groomers. Four billion dollars is spent annually for prescription flea treatment and $348 million for flea pest control

Roaches Back to Top

German CockroachesWikipedia
German Cockroaches Credit: Lmbuga, Wikipedia

The German cockroach (Blattella germanica) is a small species of cockroach, typically about 1.1 to 1.6 cm (0.43 to 0.63 in) long. In colour it varies from tan to almost black, and it has two dark, roughly parallel, streaks on the pronotum running anteroposteriorly from behind the head to the base of the wings. Although B. germanica has wings, it can barely fly, although it may glide when disturbed. Of the few species of cockroach that are domestic pests, it probably is the most widely troublesome example. It is very closely related to the Asian cockroach, and to the casual observer, the two appear nearly identical and may be mistaken for each other. However, the Asian cockroach is attracted to light and can fly rather like a moth, while the German cockroach cannot.

The German cockroach occurs widely in human buildings, but is particularly associated with restaurants, food processing facilities, hotels, and institutional establishments such as nursing homes. In cold climates, they occur only near human dwellings, because they cannot survive severe cold. However, though they would soon die in the outdoors on their own, German cockroaches have been found as inquilines ("tenants") of human buildings as far north as Alert, Nunavut. Similarly, they have been found as far south as southern Patagonia.

Previously thought to be a native of Europe, the German cockroach later was considered to have emerged from the region of Ethiopia in Northeast Africa, but more recent evidence suggests that it actually originated in Southeast Asia. Whatever the truth of the matter, the cockroach's sensitivity to cold might reflect its origin from such warm climates, and its spread as a domiciliary pest since ancient times has resulted from incidental human transport and shelter. The species now is cosmopolitan in distribution, occurring as a household pest on all continents except Antarctica, and on many major islands, as well. It accordingly has been given various names in the cultures of many regions. For example, although it is widely known as the "German cockroach" in English-speaking countries, in Germany in turn, it is known as the Russian roach.

Though nocturnal, the German cockroach occasionally appears by day, especially if the population is crowded or has been disturbed. However, sightings are most frequent of an evening, when someone suddenly brings a light into a room deserted after dark, such as a kitchen where they have been scavenging. When excited or frightened, the species emits an unpleasant odor.

German cockroaches are omnivorous scavengers. They are attracted particularly to meats, starches, sugars, and fatty foods. Where a shortage of foodstuffs exists, they may eat household items such as soap, glue, and toothpaste. In famine conditions, they turn cannibalistic, chewing at each other's wings and legs.

The German cockroach reproduces faster than any other residential cockroach, growing from egg to reproductive adult in roughly 50 – 60 days. Once fertilized, a female German cockroach develops an ootheca in her abdomen. The abdomen swells as her eggs develop, until the translucent tip of the ootheca begins to protrude from the end of her abdomen, and by that time the eggs inside are fully sized, about 1/4 inch long with 16 segments. The ootheca, at first translucent, soon turns white and then within a few hours it turns pink, progressively darkening until, some 48 hours later, it attains the dark red-brown of the shell of a chestnut. The ootheca has a keel-like ridge along the line where the young emerge, and curls slightly towards that edge as it completes its maturation. A small percentage of the nymphs may hatch while the ootheca is still attached to the female, but the majority emerge some 24 hours after it has detached from the female's body. The newly hatched 3-mm-long black nymphs then progress through six or seven instars before becoming sexually mature, but ecdysis is such a hazardous process that nearly half the nymphs die of natural causes before reaching adulthood. Molted skins and dead nymphs are soon eaten by living nymphs present at the time of molting.

Oriental CockroachWikipedia
Oriental Cockroach Credit: Project Gutenberg, Wikipedia

The oriental cockroach (Blatta orientalis), also known as the waterbug or black beetle, is a large species of cockroach, adult males being 18–29 mm (0.71–1.14 in) and adult females being 20–27 mm (0.79–1.06 in). It is dark brown or black in color and has a glossy body. The female has a somewhat different appearance from the male, appearing to be wingless at casual glance, but is brachypterous, having non-functional wings just below her head. She has a wider body than the male. The male has long wings, which cover two-thirds of the abdomen and are brown in color, and has a narrower body. Both sexes are flightless. The female oriental cockroach looks somewhat similar to the Florida woods cockroach, and may be mistaken for it. Originally endemic to the Crimean Peninsula and the region around the Black Sea and Caspian Sea, its distribution is now cosmopolitan.

Oriental cockroaches tend to travel somewhat more slowly than other species. They are often called "waterbugs" since they prefer dark, moist places. They can often be found around decaying organic matter, and in sewers, drains, damp basements, porches, and other damp locations. They can be found outside in bushes, under leaf groundcover, under mulch, and around other damp places outdoors. They are major household pests in parts of the Northwest, Midwest, and Southern United States.

To thrive, cockroaches need a place to hide. They prefer warm places and a relatively high humidity; they also need a source of food/liquid. The optimum temperature for oriental cockroaches is between 20 and 29 °C (68 and 84 °F). Female oriental cockroaches have vestigial tegmina (reduced fore wings) and males have longer tegmina. Cockroaches are mainly nocturnal. Oriental cockroaches can be elusive in that a casual inspection of an infested dwelling during the day may show no signs of roach activity. Oriental cockroaches can be found in usually damp places such as sewer pipes, sink drains, and any other form of damp areas in households.

Signs of cockroaches are their oothecae, which are “egg cases”. The blackish-brown oothecae of the oriental cockroach are 10–12 mm (0.39–0.47 in) long, with indistinct egg compartments housing 16–18 eggs. These oothecae are formed a day after mating, and typically deposited a day or two after formation, though can be deposited up to 7 days later, typically in a sheltered area or attached to a substrate by oral secretion. They are initially a yellow white, turning reddish- then blackish-brown. They lose viability at temperatures below 0 °C (32 °F). They hatch on their own in about 42 days at 29.5 °C (85.1 °F) and 81 days at 21 °C (70 °F)

American CockroachWikipedia
American Cockroach Credit: Gary Alpert, Wikipedia

The American cockroach (Periplaneta americana), also colloquially known as the waterbug, but not a true waterbug since it is not aquatic, or misidentified as the palmetto bug (see Florida woods cockroach for the differences), is the largest species of common cockroach, and often considered a pest. It is also known as the ship cockroach, kakerlac, and Bombay canary. They are native to Africa and the Middle East. Despite their name, they are believed to have been introduced to America and the New World only from the 17th century AD onwards as a result of human commercial patterns.

Of all common cockroach species, the American cockroach has the largest body size; molts 6–14 times(mostly 13 times) before metamorphosis; and has the longest lifecycle, up to about 700 days.

It has an average length around 4 cm (1.6 in) and is about 7 mm (0.28 in) tall. They are reddish brown and have a yellowish margin on the pronotum, the body region behind the head. Immature cockroaches resemble adults except they are wingless.

The cockroach is divided in three sections; the body is flattened and broadly oval, with a shield-like pronotum covering its head. A pronotum is a plate-like structure that covers all or part of the dorsal surface of the thorax of certain insects. They also have chewing mouth parts, long, segmented antennae, and leathery fore wings with delicate hind wings. The third section of the cockroach is the abdomen.

The insect can travel quickly, often darting out of sight when a threat is perceived, and can fit into small cracks and under doors despite its fairly large size. It is considered one of the fastest running insects.

In an experiment, a P. americana registered a record speed of 5.4 km/h (3.4 mph), about 50 body lengths per second, which would be comparable to a human running at 330 km/h (210 mph).

It has a pair of large compound eyes, each having over 2000 individual lenses (ommatidia, hexagonal apertures which provide a kind of vision known as the mosaic vision with more sensitivity but less resolution, being common during night, hence called nocturnal vision.), and is a very active night insect that shuns light.

American cockroach nymphs are capable of limb regeneration.

American cockroaches have three developmental stages: egg, nymph, and adult. Females produce an egg case (ootheca) which protrudes from the tip of the abdomen. On average, females produce 9–10 ootheca, although they can sometimes produce as many as 90. After about two days, the egg cases are placed on a surface in a safe location. Egg cases are about 0.9 cm (0.35 in) long, brown, and purse-shaped. Immature cockroaches emerge from egg cases in 6–8 weeks and require 6–12 months to mature. After hatching, the nymphs feed and undergo a series of 13 moultings (or ecdysis). Adult cockroaches can live up to an additional year, during which females produce an average of 150 young. The American cockroach reproductive cycle can last up to 600 days; it is capable of reproduction through facultative parthenogenesis.

American cockroaches are omnivorous and opportunistic feeders that eat materials such as cheese, beer, tea, leather, bakery products, starch in book bindings, manuscripts, glue, hair, flakes of dried skin, dead animals, plant materials, soiled clothing, and glossy paper with starch sizing. They are particularly fond of fermenting foods. They have also been observed to feed upon dead or wounded cockroaches of their own or other species.

American cockroaches generally live in moist areas, but can survive in dry areas if they have access to water. They prefer high temperatures around 29 °C (84 °F) and do not tolerate low temperatures. These cockroaches are common in basements, crawl spaces, cracks and crevices of porches, foundations, and walkways adjacent to buildings. In residential areas outside the tropics, these cockroaches live in basements and sewers, and may move outdoors into yards during warm weather.

The odorous secretions produced by American cockroaches can alter the flavor of food. Also, if populations of cockroaches are high, a strong concentration of this odorous secretion can be present. Cockroaches can pick up disease-causing bacteria, such as Salmonella, on their legs and later deposit them on foods and cause food poisoning or infection if they walk on the food. House dust containing cockroach feces and body parts can trigger allergic reactions and asthma in certain individuals.

Rodents Back to Top

Norway RatWikipedia
Norway (Brown) Rat Credit: Snowmanradio, Wikipedia

The brown rat (Rattus norvegicus), also known as the common rat, street rat, sewer rat, Hanover rat, Norway rat, Norwegian rat, Parisian rat or wharf rat, is one of the best known and most common rats.

One of the largest muroids, it is a brown or grey rodent with a head and body length of up to 28 cm (11 in) long, and a slightly shorter tail. It weighs between 140 and 500 g (4.9 and 17.6 oz). Thought to have originated in northern China, this rodent has now spread to all continents except Antarctica, and is the dominant rat in Europe and much of North America, making it by at least this particular definition the most successful mammal on the planet alongside humans. With rare exceptions, the brown rat lives wherever humans live, particularly in urban areas.

The fur is coarse and usually brown or dark grey, while the underparts are lighter grey or brown. The brown rat is a rather large murid and can weigh twice as much as a black rat (Rattus rattus) and many times more than a house mouse (Mus musculus). The head and body length ranges from 15 to 28 cm (5.9 to 11.0 in) while the tail ranges in length from 10.5 to 24 cm (4.1 to 9.4 in), therefore being shorter than the head and body. Adult weight ranges from 140 to 500 g (4.9 to 17.6 oz). Exceptionally large individuals can reportedly reach 900 to 1,000 g (32 to 35 oz) but are not expected outside of domestic specimens. Stories of rats attaining sizes as big as cats are exaggerations, or misidentifications of larger rodents, such as the coypu and muskrat. In fact, it is common for breeding wild brown rats to weigh (sometimes considerably) less than 300 g (11 oz).

Brown rats have acute hearing, are sensitive to ultrasound, and possess a very highly developed olfactory sense. Their average heart rate is 300 to 400 beats per minute, with a respiratory rate of around 100 per minute. The vision of a pigmented rat is poor, around 20/600, while a non-pigmented (albino) with no melanin in its eyes has both around 20/1200 vision and a terrible scattering of light within its vision. Brown rats are dichromates which perceive colors rather like a human with red-green colorblindness, and their colour saturation may be quite faint. Their blue perception, however, also has UV receptors, allowing them to see ultraviolet lights that some species cannot.

The brown rat is a true omnivore and will consume almost anything, but cereals form a substantial part of its diet.

Martin Schein, founder of the Animal Behavior Society in 1964, studied the diet of brown rats and came to the conclusion that the most-liked foods of brown rats include scrambled eggs, macaroni and cheese, raw carrots, and cooked corn kernels. According to Schein, the least-liked foods were raw beets, peaches, and raw celery.

Foraging behavior is often population-specific, and varies by environment and food source. Brown rats living near a hatchery in West Virginia catch fingerling fish. Some colonies along the banks of the Po River in Italy will dive for mollusks, a practice demonstrating social learning among members of this species. Rats on the island of Norderoog in the North Sea stalk and kill sparrows and ducks.

Roof RatWikipedia
Roof (Black) Rat Credit: Kilessan, Wikipedia

The black rat (Rattus rattus), also known as the ship rat, roof rat, house rat, is a common long-tailed rodent of the genus Rattus (rats) in the subfamily Murinae.

Black rats are generalist omnivores. They are serious pests to farmers as they eat a wide range of agricultural crops.

A typical adult black rat is 12.75 to 18.25 cm (5.0 to 7.2 in) long, not including a 15 to 22 cm (5.9 to 8.7 in) tail, and weighs 75 to 230 g (0.165 to 0.507 lb), depending on the subspecies. Despite its name, the black rat exhibits several colour forms. It is usually black to light brown in colour with a lighter underside. In England during the 1920s, several variations were bred and shown alongside domesticated brown rats. This included an unusual green tinted variety. The black rat also has a scraggly coat of black fur, and is slightly smaller than the brown (Norway) rat.

Black rats are considered omnivores and eat a wide range of foods, including seeds, fruit, stems, leaves, fungi, and a variety of invertebrates and vertebrates. They are generalists, and thus not very specific in their food preferences, which is indicated by their tendency to feed on any meal provided for cows, swine, chickens, cats, and dogs. They are similar to the tree squirrel in their preference of fruits and nuts. They eat about 15 grams (0.53 oz) per day and drink about 15 millilitres (0.53 imp fl oz; 0.51 US fl oz) per day. Their diet is high in water content. They are a threat to many natural habitats because they feed on birds and insects. They are also a threat to many farmers, since they feed on a variety of agricultural-based crops, such as cereals, sugar cane, coconuts, cocoa, oranges, and coffee beans.

Through the usage of tracking devices such as radio transmitters, rats have been found to occupy dens located in trees, as well as on the ground. In Puketi, a forest in Kauri, New Zealand, rats have been found to form dens together. Rats appear to den and forage in separate areas in their home range depending on the availability of food resources. Research shows that, in New South Wales, the black rat prefers to inhabit lower leaf litter of forest habitat. There is also an apparent correlation between the canopy height and logs and the presence of black rats. This correlation may be a result of the distribution of the abundance of prey as well as available refuges for rats to avoid predators. As found in North Head, New South Wales, there is positive correlation between rat abundance, leaf litter cover, canopy height, and litter depth. All other habitat variables showed little to no correlation. While this species' relative, the brown (Norway) rat prefers to nest near the ground of a building the black rat will prefer the upper floors and roof. Because of this habit they have been given the common name roof rat.

As generalists, black rats express great flexibility in their foraging behavior. They are predatory animals and adapt to different micro-habitats. They often meet and forage together in close proximity within and between sexes. Rats tend to forage after sunset. If the food cannot be eaten quickly, they will search for a place to carry and hoard to eat at a later time. Although black rats eat a broad range of foods, they are highly selective feeders; only a restricted number of the foods they eat are dominant foods. When black rat populations are presented with a wide diversity of foods, they eat only a small sample of each of the available foods. This allows them to monitor the quality of foods that are present year round, such as leaves, as well as seasonal foods, such as herbs and insects. This method of operating on a set of foraging standards ultimately determines the final composition of their meals. Also, by sampling the available food in an area, the rats maintain a dynamic food supply, balance their nutrient intake, and avoid intoxication by secondary compounds.

After Rattus rattus was introduced into the northern islands of New Zealand, they fed on the seedlings adversely affecting the ecology of the islands. Even after eradication of R. rattus, the negative effects may take decades to reverse. When consuming these seabirds and seabird eggs, these rats reduce the pH of the soil. This harms plant species by reducing nutrient availability in soil, thus decreasing the probability of seed germination. For example, research conducted by Hoffman et al. indicates a large impact on 16 indigenous plant species directly preyed on by R. rattus. These plants displayed a negative correlation in germination and growth in the presence of black rats. Rats prefer to forage in forest habitats. In the Ogasawara islands, they prey on the indigenous snails and seedlings. Snails that inhabit the leaf litter of these islands showed a significant decline in population on the introduction of Rattus rattus. The black rat shows a preference for snails with larger shells (greater than 10 mm), and this led to a great decline in the population of snails with larger shells. A lack of prey refuges makes it more difficult for the snail to avoid the rat.

House MouseWikipedia
House Mouse Credit: Public Domain, Wikipedia

The house mouse (Mus musculus) is a small mammal of the order Rodentia, characteristically having a pointed snout, small rounded ears, and a long naked or almost hairless tail. It is one of the most abundant species of the genus Mus. Although a wild animal, the house mouse mainly lives in association with humans.

The house mouse has been domesticated as the pet or fancy mouse, and as the laboratory mouse, which is one of the most important model organisms in biology and medicine. The complete mouse reference genome was sequenced in 2002. Laboratory mice derived from the house mouse are by far the most common mammalian species used in genetically engineered models for scientific research.

House mice have an adult body length (nose to base of tail) of 7.5–10 cm (3.0–3.9 in) and a tail length of 5–10 cm (2.0–3.9 in). The weight is typically 40–45 g (1.4–1.6 oz). In the wild they vary in colour from light to dark agouti (light to dark brown), but domesticated fancy mice and laboratory mice are produced in many colors ranging from white to champagne to black. They have short hair and some, but not all, sub-species have a light belly. The ears and tail have little hair. The hind feet are short compared to Apodemus mice, only 15–19 mm (0.59–0.75 in) long; the normal gait is a run with a stride of about 4.5 cm (1.8 in), though they can jump vertically up to 45 cm (18 in). The voice is a high-pitched squeak. House mice thrive under a variety of conditions; they are found in and around homes and commercial structures, as well as in open fields and agricultural lands.

Newborn males and females can be distinguished on close examination as the anogenital distance in males is about double that of the female. From the age of about 10 days, females have five pairs of mammary glands and nipples; males have no nipples. When sexually mature, the most striking and obvious difference is the presence of testicles on the males. These are large compared to the rest of the body and can be retracted into the body.

The tail, which is used for balance, has only a thin covering of hair as it is the main peripheral organ of heat loss in thermoregulation along with—to a lesser extent—the hairless parts of the paws and ears. Blood flow to the tail can be precisely controlled in response to changes in ambient temperature using a system of arteriovenous anastomoses to increase the temperature of the skin on the tail by as much as 10 °C to lose body heat. Tail length varies according to the environmental temperature of the mouse during postnatal development, so mice living in colder regions tend to have shorter tails. The tail is also used for balance when the mouse is climbing or running, or as a base when the animal stands on its hind legs (a behaviour known as tripoding), and to convey information about the dominance status of an individual in encounters with other mice.

In addition to the regular pea-sized thymus organ in the chest, house mice have a second functional pinhead-sized thymus organ in the neck next to the trachea.

House mice usually run, walk, or stand on all fours, but when eating, fighting, or orienting themselves, they rear up on their hind legs with additional support from the tail - a behavior known as "tripoding". Mice are good jumpers, climbers, and swimmers, and are generally considered to be thigmotactic, i.e. usually attempts to maintain contact with vertical surfaces.

Mice are mostly crepuscular or nocturnal; they are averse to bright lights. The average sleep time of a captive house mouse is reported to be 12.5 hours per day. They live in a wide variety of hidden places near food sources, and construct nests from various soft materials. Mice are territorial, and one dominant male usually lives together with several females and young. Dominant males respect each other's territories and normally enter another's territory only if it is vacant. If two or more males are housed together in a cage, they often become aggressive unless they have been raised together from birth.

House mice primarily feed on plant matter, but are omnivorous.[citation needed] They eat their own faeces to acquire nutrients produced by bacteria in their intestines. House mice, like most other rodents, do not vomit.

Mice are generally afraid of rats which often kill and eat them, a behavior known as muricide. Despite this, free-living populations of rats and mice do exist together in forest areas in New Zealand, North America, and elsewhere. House mice are generally poor competitors and in most areas cannot survive away from human settlements in areas where other small mammals, such as wood mice, are present. However, in some areas (such as Australia), mice are able to coexist with other small rodent species.

Female house mice have an estrous cycle about four to six days long, with estrus itself lasting less than a day. If several females are held together under crowded conditions, they will often not have an estrus at all. If they are then exposed to male urine, they will come into estrus after 72 hours.

Male house mice court females by emitting characteristic ultrasonic calls in the 30 kHz–110 kHz[citation needed] range. The calls are most frequent during courtship when the male is sniffing and following the female; however, the calls continue after mating has begun, at which time the calls are coincident with mounting behaviour. Males can be induced to emit these calls by female pheromones. The vocalizations appear to differ between individuals and have been compared to bird songs because of their complexity. While females have the capability to produce ultrasonic calls, they typically do not do so during mating behaviour.

Following copulation, female mice will normally develop a copulation plug which prevents further copulation. The plug is not necessary for pregnancy initiation, as this will also occur without the plug. The presence or absence of the plug will not affect litter size either. This plug stays in place for some 24 hours. The gestation period is about 19–21 days, and they give birth to a litter of 3–14 young (average six to eight). One female can have 5 to 10 litters per year, so the mouse population can increase very quickly. Breeding occurs throughout the year. (However, animals living in the wild do not reproduce in the colder months, even though they do not hibernate.)

The pups are born blind and without fur or ears. The ears are fully developed by the fourth day, fur begins to appear at about six days and the eyes open around 13 days after birth; the pups are weaned at around 21 days. Females reach sexual maturity at about six weeks of age and males at about eight weeks, but both can copulate as early as five weeks. If the infants live in high temperatured area from birth, they will become less-haired.

Spiders Back to Top

Black WidowsWikipedia
Black Widow Credit: Bloomingdedalus, Wikipedia

The female black widow spider is considered the most venomous spider in North America. The venom of the black widow spider is 15 times as toxic as the venom of the prairie rattlesnake.

Only the female black widow is dangerous to humans; males and juveniles are harmless. The female black widow will, on occasion, kill and eat the male after mating. More than 35,000 species of spiders occur worldwide. About 3,400 species of spiders in 64 families are found in North America.

Both western and eastern black widows spin webs that lack shape and form. Their webs are erratic in appearance, and the silk is stronger than almost all other arachnids. The webs are rough and sticky. The black widow spider is shy and nocturnal in habit, usually staying hidden in her web, hanging belly upward. Although not aggressive, she may rush out and bite when her web is disturbed.

Black widows are found on the underside of ledges, rocks, plants and debris, wherever a web can be strung. Cold weather or drought may drive these spiders into buildings.

Adult male black widows wander in search of females but do not bite. Females may occasionally kill and eat a male after mating but this is more the exception than the rule.

The female lays several batches of eggs, containing up to 750 eggs each, in one summer. The egg case, about .5 inch in diameter, is suspended in the web. It is white to tan in color and has a paper-like texture. There may be four to nine egg sacs produced during a summer. Young black widows are colored orange and white when they emerge 1 to 4 weeks later. Normally, only one to twelve young survive after the egg incubation period of 14 to 30 days, due to cannibalism by their fellow spiderlings.

Wolf SpiderWikipedia
Wolf Spider Credit: Patrick Edwin Moran, Wikipedia

Wolf spiders are members of the family Lycosidae, from the Ancient Greek word "λύκος" meaning "wolf". They are robust and agile hunters with excellent eyesight. They live mostly in solitude and hunt alone, and do not spin webs. Some are opportunistic hunters pouncing upon prey as they find it or even chasing it over short distances. Some will wait for passing prey in or near the mouth of a burrow.

Wolf spiders resemble nursery web spiders (family Pisauridae), but wolf spiders carry their egg sacs by attaching them to their spinnerets. (Pisauridae carry their egg sacs with their chelicerae and pedipalps). Two of the wolf spider's eight eyes are large and prominent, which distinguishes them from the nursery web spiders whose eyes are all of approximately equal size. This can also help distinguish them from grass spiders.

Wolf spiders will inject venom if continually provoked. Symptoms of their venomous bite include swelling, mild pain, and itching. In the past, necrotic bites have been attributed to some South American species, but further investigation has indicated that those problems that did occur were probably actually due to bites by members of other genera.[3] Australian wolf spiders have also been associated with necrotic wounds, but careful study has likewise shown them not to produce such results.[4]

Wolf spiders can be found in a wide range of habitats both coastal and inland. These include shrublands, woodland, wet coastal forest, alpine meadows, suburban gardens, and homes. Spiderlings disperse aerially and consequently wolf spiders have wide distributions. Although some species have very specific microhabitat needs (such as stream-side gravel beds or montane herb-fields) most are wanderers without permanent homes. Some build burrows which can be left open or have a trapdoor (depending on species). Arid zone species construct turrets or plug their holes with leaves and pebbles during the rainy season to protect themselves from flood waters.

Cellar Spider ("Daddy Long-legs")Wikipedia
Cellar Spider ("Daddy Long-legs") Credit: Olaf Leillinger, Wikipedia

Pholcus phalangioides, known as the longbodied cellar spider or the skull spider due to its cephalothorax looking like a human skull, is a spider of the family Pholcidae. Females have a body length of about 9 mm; males are slightly smaller. Its legs are about 5 or 6 times the length of its body (reaching up to 7 cm of leg span in females). Its habit of living on the ceilings of rooms, caves, garages or cellars gives rise to one of its common names. They are considered beneficial in some parts of the world because they kill and eat other spiders, including species that can be considered a problem to humans such as hobo and redback spiders.

This is the only spider species described by the Swiss entomologist Johann Kaspar Füssli, who first recorded it for science in 1775. Confusion often arises over its common name, because "daddy long-legs" is also applied to two other distantly related arthropods: one being Opiliones, another order of arachnid known also as a "harvestman", the other an insect less ambiguously called the crane fly.

Originally a species restricted to warmer parts of the west Palearctic,[4][better source needed] through the help of humans this synanthrope now occurs throughout a large part of the world.[1][better source needed] It is unable to survive in cold weather, and consequently it is restricted to (heated) houses in some parts of its range.

Pholcus phalangioides is not considered aggressive, its first line of defense being to shake its web violently when disturbed as a mechanism against predators. It can easily catch and eat other spiders (even those much larger than itself, such as Eratigena atrica, mosquitoes and other insects, and woodlice. When food is scarce, it will prey on its own kind. Rough handling will cause some of its legs to become detached.

Peak breeding in this species occurs between June and September. The female holds the 20 to 30[citation needed] eggs in her pedipalps. Spiderlings are transparent with short legs, and change their skin about 5 or 6 times as they mature.

An urban legend states that Pholcidae are the most venomous spiders in the world but that it is nevertheless harmless to humans because its fangs cannot penetrate human skin. Both of these claims have been proven untrue. Recent research has shown that pholcid venom has a relatively weak effect on insects.[6] In the MythBusters episode "Daddy Long-Legs" it was shown that the spider's fangs (0.25 mm) could penetrate human skin (0.1 mm), but that only a very mild burning feeling was felt for a few seconds.[7]

WaspsBack to Top

Paper WaspsWikipedia
Paper Wasp Credit: Alvesgaspar, Wikipedia

Paper wasps are vespid wasps that gather fibers from dead wood and plant stems, which they mix with saliva, and use to construct water-resistant nests made of gray or brown papery material. Some types of paper wasps are also sometimes called umbrella wasps, due to the distinctive design of their nests.

The nests of most true paper wasps are characterized by having open combs with cells for brood rearing, and a 'petiole', or constricted stalk, that anchors the nest. Paper wasps secrete a chemical which repels ants, which they spread around the base of the anchor to prevent the loss of eggs or brood.

Most social wasps of the family Vespidae make nests from paper, but some stenogastrine species, such as Liostenogaster flavolineata, use mud. A small group of eusocial crabronid wasps, of the genus Microstigmus (the only eusocial wasps outside the family Vespidae), also constructs nests out of chewed plant fibers, though the nest consistency is quite different from those of true paper wasps, due to the absence of wood fibers, and the use of silk to bind the fibers.

Nests can be found in sheltered areas, such as the eaves of a house, the branches of a tree, on the end of an open pipe, or on an old clothesline. Some species, such as Ropalidia romandi, will vary their nest architecture depending on where they build their nest.

Three species of Polistes are obligate social parasites, and have lost the ability to build their own nests, and are sometimes referred to as "cuckoo paper wasps". They rely on the nests of their hosts to raise their brood.

Unlike yellowjackets and hornets, which can be very aggressive, polistine paper wasps will generally only attack if they themselves or their nest are threatened. Since their territoriality can lead to attacks on people, and because their stings are quite painful and can produce a potentially fatal anaphylactic reaction in some individuals, nests in human-inhabited areas may present an unacceptable hazard.

Most wasps are beneficial in their natural habitat, and are critically important in natural biocontrol. Paper wasps feed on nectar and other insects, including caterpillars, flies, and beetle larvae. Because they are a known pollinator and feed on known garden pests, paper wasps are often considered to be beneficial by gardeners.

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